1. Field of the Invention
The present invention relates to earphones, especially to an earphone with adjustable impedance.
2. General Background
Generally, when using a media players in a public place, the user can use an earphone to avoid disturbing other people around. However, different multimedia players have different output impedances, for example, the output impedance of the earphone jack of the video compact disc (VCD) player, digital video disc (DVD) player and TVs are about 200 ohm or higher, the output impedance of the earphone jack of the MP3 player and MiniDisc (MD) player is about 50 ohm or lower. If an earphone with low impedance is insert into the earphone jack of the VCD player, DVD player and TVs and the like, the earphone with low impedance will be over loading and resulted in damage, and if an earphone with high impedance is insert into the earphone jack of the MP3 player and the MD player, the earphone with high impedance is difficult to drive to output an audible sound. So earphones with high or mid-range impedance are compatible with the VCD player, DVD player, and the TVs; earphones with low impedance are suitable for portable electronic media players, such MP3 player and MD player. As a result, when a user possesses different types of media players, the user must buy earphones with different impedance to match the media players, which will raise cost to the user.
Therefore, it is necessary to provide an earphone can match a plurality of media players.